Added support for non-lowercase ENVI header parameter names.

* spectral.py (Settings): Added envi_support_nonlowercase_params member.
* io/envi.py (read_envi_header): Provide support for non-lowercase parameter
  names. Display warning when names are converted to lower case.
* tests/envi.py: Added tests for non-lowercase ENVI header parameter names.

Author: tboggs

spectral/io/envi.py

@@ -132,6 +132,8 @@ def read_envi_header(file):
     dictionary as strings.  Header field names are treated as case
     insensitive and all keys in the dictionary are lowercase.
     '''
+    import warnings
+    from spectral import settings
     f = builtins.open(file, 'r')
 
     try:
@@ -152,14 +154,20 @@ def read_envi_header(file):
     f.close()
 
     dict = {}
+    have_nonlowercase_param = False
+    support_nonlowercase_params = settings.envi_support_nonlowercase_params
     try:
         while lines:
             line = lines.pop(0)
             if line.find('=') == -1: continue
             if line[0] == ';': continue
 
             (key, sep, val) = line.partition('=')
-            key = key.strip().lower()
+            key = key.strip()
+            if not key.islower():
+                have_nonlowercase_param = True
+                if not support_nonlowercase_params:
+                    key = key.lower()
             val = val.strip()
             if val and val[0] == '{':
                 str = val.strip()
@@ -178,6 +186,14 @@ def read_envi_header(file):
             else:
                 dict[key] = val
 
+        if have_nonlowercase_param and not support_nonlowercase_params:
+            msg = 'Parameters with non-lowercase names encountered ' \
+                  'and converted to lowercase. To retain source file ' \
+                  'parameter name capitalization, set ' \
+                  'spectral.setttings.envi_support_nonlowercase_params to ' \
+                  'True.'
+            warnings.warn(msg)
+            print('Header parameter names converted to lower case.')
         return dict
     except:
         raise EnviHeaderParsingError()

spectral/spectral.py

@@ -53,6 +53,12 @@ class SpySettings:
             If calls to `view_cube` or `view_nd` result in windows with blank
             canvases, try reducing this value.
 
+        `envi_support_nonlowercase_params` (bool, default False)
+
+            By default, ENVI headers are read with parameter names converted
+            to lower case. If this attribute is set to True, parameters will
+            be read with original capitalization retained.
+
         `show_progress` (bool, default True):
     
             Indicates whether long-running algorithms should display progress
@@ -123,6 +129,8 @@ class SpySettings:
     # canvas does not render, try reducing this value (e.g., 16).
     WX_GL_DEPTH_SIZE = 24
 
+    envi_support_nonlowercase_params = False
+
     # Should algorithms show completion progress of algorithms?
     show_progress = True
 

spectral/tests/envi.py

@@ -43,6 +43,18 @@
 from .spytest import SpyTest
 from spectral.tests import testdir
 
+MIXED_CASE_HEADER = '''ENVI
+samples = 145
+lines = 145
+bands = 220
+header offset = 0
+file type = ENVI Standard
+data type = 4
+interleave = bip
+byte order = 0
+some Param = 0
+'''
+
 class ENVIWriteTest(SpyTest):
     '''Tests that SpyFile memmap interfaces read and write properly.'''
     def __init__(self):
@@ -265,6 +277,28 @@ def test_header_missing_mandatory_parameter_fails(self):
         else:
             raise Exception('Failed to raise EnviMissingHeaderParameter')
 
+    def test_param_name_converted_to_lower_case(self):
+        '''By default, parameter names are converted to lower case.'''
+        import spectral as spy
+        header = 'mixed_case_header.hdr'
+        open(header, 'w').write(MIXED_CASE_HEADER)
+        h = spy.envi.read_envi_header(header)
+        assert('some param' in h)
+
+    def test_support_nonlowercase_params(self):
+        '''By default, parameter names are converted to lower case.'''
+        import spectral as spy
+        from spectral import settings
+        header = 'mixed_case_header.hdr'
+        open(header, 'w').write(MIXED_CASE_HEADER)
+        orig = settings.envi_support_nonlowercase_params
+        try:
+            settings.envi_support_nonlowercase_params = True
+            h = spy.envi.read_envi_header(header)
+        finally:
+            settings.envi_support_nonlowercase_params = orig
+        assert('some Param' in h)
+
     def test_missing_ENVI_in_header_fails(self):
         '''FileNotAnEnviHeader should be raised if "ENVI" not on first line.'''
         import os